They previously had a number one record in Britain, although that was almost 45 years ago.

Frontman Ozzy was astounded by the success, even though he had a feeling there was something special about the release.

"What the f**k is this? Who the f**k gets their first number one album 45 years into their f**king careers?' Ozzy joked he thought when he was told.

"I'm a terrible critic of myself. I rip my own albums apart. But when I heard this finished, I said to my wife [Sharon], I don't know what they did. It hit me like a sledgehammer.'

13 is the band's first album since 1995's Forbidden. Although the group - comprising of Ozzy, Tony Iommi and Geezer Butler - had tried to record on many occasions since then, it never worked out.

One reason was the reality TV show following Ozzy's family which aired between 2002 and 2005. Looking back, he regrets allowing cameras into his home for The Osbournes.

"My wife wanted to be on TV,' he told New York Daily News. 'I never went into this so I could become a f**king weatherman on TV.

"[It wasn't that real.] You never saw me when I was face down on the f**king floor."

After the men announced they were working together again, Tony discovered he had cancer. He told Ozzy about his fears and the whole band were worried, but the guitarist found working while ill helped him.

"He came to my house and said, 'I got this lump in my groin,'' Ozzy explained. 'He was putting off having it checked out. He didn't want to face up to it.

"Doing the album took Tony's mind off the cancer. He's a strong guy. He used to smoke cigarettes and just stopped. He's got tremendous will power."